1. Field of the Invention
The present invention relates to a transfusion pump such as a peristaltic pump or roller pump to pump fluids such as liquid medicine.
2. The Prior Art
A conventional transfusion pump comprises a housing body, a door supported on the housing body for pivotal movement between an open position and a closed position, a tube pressing means disposed in the housing body, a platen disposed on the door so as to support a tube against the tube pressing motion of the tube pressing means when the door is closed, and a door locking member for locking the door to the housing body.
In this transfusion pump, an elastic tube is intermittently collapsed between the platen and the tube pressing means by means of the same tube pressing means, whereby a liquid in the tube is displaced and transported, while the tube is allowed to return to its original shape each time the pressing force applied thereon is released so as to expand the liquid passage. Thus, the pump can provide a pumping action.
By the way, a transfusion pump is used for the purpose of accurately feeding a small amount of transfusion liquid to the body of a patient, thereby ensuring the safety of the patient. Thus, it must be strictly prevented that the transfusion liquid is allowed to flow under no control, when the transfusion pump is used.
In a conventional transfusion pump, accordingly a tube clamp device as shown in FIG. 9 is used. The conventional tube clamp device comprises a tube receiving member 2 disposed on a housing body 1, a clamping member 3 disposed for rotation about a fulcrum 3A provided on the housing body 1, which can clamp a tube 4 between the tube receiving member 2 and the clamping member 3, an urging member 5 for urging the clamping member 3 toward the tube receiving member 2, a retaining lever 6 disposed on the housing body 1, which can retain the clamping member 3 in an unclamped position where the tube 4 is, an unclamped retaining portion 8 provided on a door 7, and a pin 9 inserted in a supporting hole 9A provided in the housing body 1, which is pushed by the unclamped retaining portion 8 of the door 7 when the door 7 is closed so as to retain the clamping member 3 in the unclamp position where the tube 4 is unclamped. In addition, the clamping member 3 is provided with an adjusting screw 3B at a portion thereof that collides the pin 9, and an urging member 6A is disposed between the housing body 1 and the retaining lever 6, which causes the retaining lever 6 to move from a position where it is engaged with the clamping member 3.
The tube clamp device which has the aforementioned constitution will be operated as described in the following items (1) to (3).
(1) When the door 7 is opened to set a tube 4 in the device, the retaining lever 6 is pushed to set the clamping member 3 at the unclamped position thereof. In this state, the retaining lever 6 rotates about the fulcrum 6B to engage its end with the concave part of the clamping member 3 so that the clamping member 3 is retained in the unclamped position.
(2) When a tube 4 is set in place and the door 7 is closed to start a transfusion of liquid, the unclamped retaining member 8 of the door 7 pushes the pin 9 and this pin 9 further collides with the adjusting screw 3B of the clamping member 3 so that the clamping member 3 is moved in an unclamping direction.
After the clamping member 3 is further opened to the unclamping direction, the end of the retaining lever 6 and the concave part of the clamping member 3 are disengaged so that the retaining lever 6 is returned to a position where it is not engaged with the clamping member 3 by means of the urging member 6A.
As long as the door 7 is kept closed in this state, the clamping member 3 collides with the pin 9 so as to be continuously retained in the unclamped position, whereby the transfusion pump imparts the pumping action to the tube that is kept in the unclampled state, thus carrying out the transfusion of liquid.
(3) When the transfusing operation is finished and the door 7 is opened, the pin 9 which is pushed by the unclampled retaining portion 8 of the door 7, is released to move freely, whereby the clamping member 3 which has already disengaged with the retaining lever 6 clamps the tube 4 between the tube receiving member 2 and the clamping member 3 by virtue of the urging member 5, thus preventing the free flow of a transfusion liquid.
In this prior art, however, there are the following problems 1 and 2.
1 Movable members provided in the housing body 1 include the clamping member 3, retaining lever 6, pin 9 and other parts. The tube clamp device may, therefore, function improperly, and requires maintenance, because of the wear of these parts over time and the need to place chemical liquid on the supporting hole 9A for the pin 9.
2 The position of the pin 9 which pushes the clamping member 3 when the door 7 is closed (the point where the clamping member 3 and the pin 9 collide with each other) is near the fulcrum 3A of the clamping member 3. The force of the unclamped retaining portion 8 of the door 7 pushing the pin 9, which overcomes the urging member 5 to press the clamping member 3 to the unclamping direction is therefore very large. This large force may cause bending the whole of the transfusion pump so that the transfusion pump as a whole may function improperly.
The present invention is intended to provide a compact tube clamp device when the tube clamp device is installed in a transfusion pump in order that a transfusion liquid is prevented from freely flowing therein. The clamp design prevents the tube clamp device from functioning improperly, and further prevents the transfusion pump as a whole from functioning improperly.